Mutable Breath: At first level, the Tome Dragon gains a breath weapon that deals 1d4 damage/HD of one of the following types: Acid, Cold, electricity, Fire, or Sonic.

I skimmed most of the Class and the abilities to get an idea of what it could do and wondered why it could use most energy types in it's breath weapon, but not Electricity. Yeah, it's just as petty as I said it'd be.

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Unlike a normal wizard, the tome dragon needs to hold the spellbook from which he prepared his magic that day to cast a spell as an additional material focus.

Nice, this reminds me of a weaker version of the Elder Titan's Hammer, as far as combat is concerned. Though I am wondering about what kind of books the Tome Dragons are allowed. Are they allowed to use Blessed Books, or are they limited to regular 100 page Spell books?

It's a dragon class. You take it instead of taking a regular class, so if you are playing gestalt, you're Tome Dragon in one side and something else on the other side. Check the Introduction and FAQ from this project for more details.

Sorry for the super necro, I was going through and reading classes, looking for nifty ideas and things. I found Tome Dragon, saw it's breath weapon basically works like a Fireball, that you can choose the element of each time you use it, with a cooldown of every single round.

So to clarify that I have this right Tome Dragon 1/Multi-Headed 5, Strange Skill Special Heads x 2, I can now breath this fireball weapon (That has a burst of 10 ft currently.) Now, if you have 5 heads using this, can each head use it's own energy type? For instance could I choose a square, and just aim Fire, Acid, Electricity, Cold and Sonic at it? I realize this is an edge case of multi-classing, but that basically means you're dealing 6d4x5 damage every round at a range of 640 ft in a 10ft burst? Just making sure I've done the math right on all of that.

It feels...uhhh kind of powerful, again I understand it's an edge case, because of the multi-classing but dang, that feels pretty potent to me. Suppose it's time would be better spent casting spells but yeah.

So to clarify that I have this right Tome Dragon 1/Multi-Headed 5, Strange Skill Special Heads x 2, I can now breath this fireball weapon (That has a burst of 10 ft currently.) Now, if you have 5 heads using this, can each head use it's own energy type? For instance could I choose a square, and just aim Fire, Acid, Electricity, Cold and Sonic at it? I realize this is an edge case of multi-classing, but that basically means you're dealing 5d4x5 damage every round at a range of 640 ft in a 10ft burst? Just making sure I've done the math right on all of that.

I do not believe that is correct, first of all, a dragon's breath attack is only usable once every 1d4 rounds.

Quote from: SRD

Using a breath weapon is a standard action. Once a dragon breathes, it can’t breathe again until 1d4 rounds later. If a dragon has more than one type of breath weapon, it still can breathe only once every 1d4 rounds.

Secondly, if multiple attacks are performed upon the same target you have to choose one attack, and this attack is performed as being 1HD higher than per head committed to the area. So, a maximum of one attack at 5d4 (1d4 for Tome Dragon 1, 4d4 for four Special Heads), not five.

Quote from: Multi-Headed Creature

Special Heads: Choose two of your Extra Heads. Those heads can now use any special attack that your original head could use, like breath weapons or gaze attacks. You can take this multiple times, each time applying to two new heads. All of your heads must use the special attack at the same time, altough they can aim at different targets. If a creature is targeted by two or more heads on the same round, it is affected only one time by the special attack, but the HD of the multi-headed creature counts as one higher for each extra head using the attack.

Thirdly, the rules seem to be clear as to whether or not a Multi-Headed Tome Dragon is capable of deciding the heads breath attack independently. The rules for the Multi-Headed template-class clearly indicate that it is one attack (the special attack and not their special attacks) and that the attack has to occur at the same time. Since all the heads have to use the breath weapon at the same time and the Tome Dragon decides the element of its breath every time it uses it, the dragon would have use the same element for all the heads.

On the other hand, it would seem thematically appropriate to allow the Tome Dragon to simply add 1d4 of elemental damage to the target, instead of increasing the level of the attack by 1. That would result in 1d4x5 of elemental damage, though this would only be a 5' burst (since the HD the breath attacks are performed at is 1), and the range would be 440' (assuming that 'large' and 'long' spell range are the same).

Quote from: Multi-Headed Creature

So for example a red dragon 1/multiheaded creature 5 using all his breath weapons on the same area would deal 10d6 damage with a reflex DC of 15+Con modifier. Alternatively he could make one heads fire in one direction dealing normal breath damage and the other two in another direction dealing 8d6 damage with a reflex DC of 14+Con modifier.

The example pertaining to breath weapons in the Multi-Headed creature just seems to be wrong, or am I missing something?

Sorry for the super necro, I was going through and reading classes, looking for nifty ideas and things. I found Tome Dragon, saw it's breath weapon basically works like a Fireball, that you can choose the element of each time you use it, with a cooldown of every single round.

So to clarify that I have this right Tome Dragon 1/Multi-Headed 5, Strange Skill Special Heads x 2, I can now breath this fireball weapon (That has a burst of 10 ft currently.) Now, if you have 5 heads using this, can each head use it's own energy type? For instance could I choose a square, and just aim Fire, Acid, Electricity, Cold and Sonic at it? I realize this is an edge case of multi-classing, but that basically means you're dealing 6d4x5 damage every round at a range of 640 ft in a 10ft burst? Just making sure I've done the math right on all of that.

It feels...uhhh kind of powerful, again I understand it's an edge case, because of the multi-classing but dang, that feels pretty potent to me. Suppose it's time would be better spent casting spells but yeah.

Added some extra clauses to the Multiheaded creature for such an edge case since indeed the multi-headed rules didn't really cover the possibility of a breath with multi-choice each time it is used. Basically each extra head would only add +1d4 damage for overlapping areas and if you use different elements then the damage is split evenly among them (so two heads breathing fire and cold would mean half the damage is fire and the other half is cold).

So for example a red dragon 1/multiheaded creature 5 using all his breath weapons on the same area would deal 10d6 damage with a reflex DC of 15+Con modifier. Alternatively he could make one heads fire in one direction dealing normal breath damage and the other two in another direction dealing 8d6 damage with a reflex DC of 14+Con modifier.

The example pertaining to breath weapons in the Multi-Headed creature just seems to be wrong, or am I missing something?

Abilities based in HD count all your HD (permanent only, no bard shenigans as per the FAQ). A dragon 1/multi-headed creature 5 has 6 HD for all their abilities.

Sweet reads well, eliminates any would-be headaches of logistics thanks for adding it, sorry to have pointed out such an edge case, as someone who runs almost only Gestalt campaigns, I tend to get a lot of edge cases for classes.